| I polled people here, spoke extensively with Seb and Greg at Specialty as well as Joe at Operation Z who are building my motor. I alos got a ride in Seb's 10 second car running 700bb's. Here are my observations (check my profile for the mods going into the build and know that my cost with labor is well north of $10k): The 500's are quick spooling, and if you are a track guy, possibly the best call. ScottZ32 in particular seems to have an amazingly agile TT and he runs the 500's with a host of other mods designed for agility as opposed to straightline numbers. If you get these by themselves, without bolstering your engine's internals, you'll be fine (though nothing near Scott's car). Any turbos discussed below will require further modification for safety and longevity. The 530's are very popular because they have nice spool up and can get you into the 400's on pump gas safely. Minimal lag, fun on the street. Versatile. Also, injectors, intake, and chipping (exhaust, downpipes, etc. will be assumed) will more or less cover you though sturdy internals would be best. I opted out on these. I felt that by spending a LOT more dough on cams, head work, internals, and fuel delivery, since I'm covered from the exhaust side, I could get almost similar spool characteristics from a larger turbo without sacrificing top end potential or running the turbos at 10/10ths of efficiency. 600's. Old-tech, don't bother. Need all kinds of mods for these, and if you are doing all of that, get a decent turbo. Gt28r: Needs fabrication to fit. Non-ball bearing, not on my list. 700BB/Gt28rs: Basically the same as a JWT BB700. .86 a/r housing, big power, big spool up. Needs custom fabbing to fit whereas the JWT does not. 700BB/GT28rs (.64 A/R). Similar top end to the larger housing but faster spool up. Greg was opposed to this choice because he felt the wheel and housing combo was not optimal and at 10/10ths, a lot of heat would be generated as well as other less than ideal drawbacks. I don't plan on running 30 lbs of boost or 9 second quarters, so I think I'll be well within safe specs. This was my pick. This set up closely approximates the HKS turbos which draw raves from almost EVERYONE, except that you must ask the money man to use protection when you double over from what they cost. A few considerations: By opting for cams, and significant headwork, I plan on minimizing lag, or else I'd have settled for the 530's. Also, Specialty is building my block, so I know it will be strong enough for the added power. Cams, and building pressure at lower wheel speeds was appealing to me, as was the lower temperatures experienced with the 500 cams. Seb's car nearly made me crap my pants (.86 a/r) but was a bit too laggy for my driving style. His 500 cams were adjusted for max top end power. My 500 cams will retain variable timing so spool up will be even better with the smaller housing. (The variable gears will wear out, but I am hoping for a solution). I'm building a bit for overkill. SO the 530's really might be the way to go. Anything over 530's and you'll be looking at $$$ for 740 cc injectors for example (or 850cc's). Anything over SP500's and you should be investing in sturdy internals, not stock or JDM. Don't ignore cooling. Sorry this is long. Many may disagree. But this was my take as a layman trying to make sense of roughly the same question. Good luck!
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1991 Aztec Red TT bought new in '91
Way back then, added JWT chip, ignition advance, Pop charger, Stainless 3pc Borla cat back; 17 in. OZ wheels
Sold 1994, 88,000 miles later, still on orig clutch; what a car 1991 Charcoal Gray TT purchased 06/05 and a heck of a lot more bang than my original.
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